1. Field of the Invention
The invention relates to an object recognition apparatus and method thereof and a radar apparatus and method thereof that recognize an object in front of a predetermined vehicle, and more particularly to an object recognition apparatus and method thereof and a radar apparatus and method thereof, which prevent misrecognition of virtual images produced by reflection of roadside objects.
2. Description of the Related Art
FIG. 1 is a diagram for illustrating how a ghost is detected by a radar apparatus in the prior art. In the past, a radar apparatus is known that transmits radar waves to an object ahead and, using waves reflected by the object, measures a distance and a relative velocity to the object. The radar apparatus on a predetermined vehicle 100, as shown in FIG. 1, is able to make a correct recognition of a distance and a relative velocity of a target vehicle 200 when it directly receives waves reflected by the target vehicle 200 ahead (a route {circle around (1)} shown in FIG. 1). However, when there exists a roadside object 300 such as a guard rail, tunnel wall, or windbreak wall, and the waves from the target vehicle 200 are reflected by the roadside object 300 (a route from {circle around (2)} to {circle around (3)} shown in FIG. 1), the radar apparatus makes an erroneous recognition as if the waves were reflected outside of the roadside object 300 (a route from {circle around (2)}xe2x80x2 to {circle around (3)} shown in FIG. 1), and detects a virtual image of a vehicle that is not really existent, that is, a ghost 210. This gives rise to a problem.
As one technique to overcome the problem, there is Japanese Patent Application Laid-open No. 2001-116839. The Japanese Application discloses an invention by which a line having a width of three lanes around a lane on which a vehicle is currently running is designated as a basic line. When three of a series of stationary objects, for example, projectors (reflectors) continuously put on guardrails, are detected inside of the basic line, a new line consisting of a series of projectors is produced as a new basic line. When there exists an object outside of the basic line, the object is decided to be a ghost, which is to be deleted.
The radar apparatus in the prior art may sometimes fail to recognize the roadside object 300. A frequency modulated continuous wave (FMCW) radar apparatus, for example, receives reflected waves, but cannot know from where in the roadside object 300 the received waves are reflected when the roadside object 300 does not have a series of projectors. As a result, a combination of FFT power spectral peaks cannot be determined, which fails to recognize the roadside object 300.
In the technique disclosed in Japanese Patent Application Laid-open No. 2001-116839, when the roadside object 300 is not recognized, the ghost 210 may sometimes be erroneously detected. For example, when a vehicle is running on a lane having the roadside object 300 and two or more of a series of projectors cannot be detected, a line having a width of three lanes is designated as a basic line. Since the ghost 210 produced outside of the roadside object 300 are present inside of the basic line, it is recognized erroneously as a correct target, which is a problem.
As mentioned above, since the radar apparatus in the prior art gives rise to the problems, there is a need to resolve the problem.
The invention is directed to an apparatus and method that satisfy the need. The invention provides an object recognition apparatus and method thereof and a radar apparatus and method thereof that can recognize a virtual image without detecting a roadside object. The radar apparatus uses radar waves for detection of an object, while the object recognition apparatus and method thereof are related to lasers and infrareds for detection of an object.
One aspect of the invention involves an object recognition apparatus. The apparatus comprises a judgment unit for judging whether an object is detected on a lane other than a lane on which a predetermined vehicle is currently running, an adjacent lane judgment unit for judging whether an adjacent lane exists adjacent to the currently running lane, and a recognition unit for recognizing that the object is a virtual image when the judgment unit has judged that the object is detected and the adjacent lane judgment unit has judged that the adjacent lane does not exist.
According to the invention, although the adjacent lane does not exist, when the object like a vehicle on a lane other than the currently running lane, for example, a lane adjacent to the currently running lane is detected, it is judged that the object is a virtual image.
Though there is no adjacent lane adjacent to the currently running lane, when the object like a vehicle is detected adjacent to the currently running lane, the invention judges that the object is a virtual image
Advantageously, the adjacent lane judgment unit designates a first area where a vehicle running on the adjacent lane at a predetermined relative speed with respect to the predetermined vehicle is detected at least once, and a second area that is outside of the currently running lane and does not overlap the first area, and when the object is detected for the first time in the second area, not in the first area, judges that the adjacent lane is not existent.
Since the first area is designated as an area where a vehicle running on the adjacent lane at a predetermined relative speed with respect to the predetermined vehicle is detected at least once, when there is an adjacent lane, the object is usually detected in the first area. Accordingly, when the object is detected for the first time in the second area, not in the first area, it is judged that the adjacent lane is not existent, and that the object is a virtual image.
When a vehicle on the adjacent lane is running at a speed more than a predetermined relative speed, since the vehicle can be detected for the first time in the second area, not in the first area, the vehicle is erroneously judged to be a virtual image.
Advantageously, when a first object has been detected in the second area for the first time, not detected in the first area, but a second object having the same distance and relative speed as the first object has not been detected on the currently running lane, the recognition unit does not recognize the first object as a virtual image. The recognition can be done because when a virtual image is produced, there always exists on the currently running lane an object that has the same distance and relative speed as a virtual image. The recognition leads to more precise judgment as to whether or not the object is the virtual image.
Advantageously, the apparatus further comprises a stationary object line judgment unit for judging whether a stationary object line is detected having a plurality of stationary objects, wherein when the stationary object line judgment unit has judged that the stationary object line is detected, the recognition unit recognizes as a virtual image an object detected outside of the stationary object line. As a result, a erroneous recognition of virtual images can be prevented.
Advantageously, when a virtual image is detected outside of the stationary object line, but a vehicle ahead is not detected that runs on the currently running lane at the same distance and relative speed as the virtual image, the recognition unit estimates a distance and a relative velocity of the vehicle ahead based on the virtual image.
Advantageously, the recognition unit estimates a distance and a relative velocity of the virtual image as the distance and the relative velocity of the vehicle ahead.
Advantageously, the recognition unit designates an area, based on the distance and the relative velocity of the virtual image, where the vehicle ahead is estimated to exits in the past, and, when the vehicle ahead is detected in the designated area, estimates a distance and a relative velocity of the vehicle ahead during a present control cycle, based on the distance and the relative velocity of the vehicle ahead detected in the past.
As mentioned above, a virtual image is recognized outside of the stationary object line, it is presumed that there is a vehicle ahead on the currently running lane that runs at the same distance and relative velocity as those of the virtual image. However, thought a virtual image is recognized outside of the stationary object line, when a vehicle ahead, which produces, is not detected on the currently running lane, it is considered that the vehicle ahead on the currently running lane is lost. Accordingly, based on the virtual image recognized outside of the stationary object line, the lost vehicle ahead is extrapolated, which enables the object on the currently running lane to be precisely recognized without being lost.
One aspect of the invention involves a radar apparatus for use on a vehicle. The apparatus comprises a transmitter for transmitting waves to an object ahead, a receiver for receiving the waves reflected by the object, a judgment unit, based on a signal from the receiver, for judging whether the object is detected on a lane other than a lane on which the vehicle is currently running, an adjacent lane judgment unit for judging whether an adjacent lane exists adjacent to the currently running lane, and a recognition unit for recognizing that the object is a virtual image when the judgment unit has judged that the object is detected and the adjacent lane judgment unit has judged that an adjacent lane does not exist. The radar apparatus has the same advantages as the object recognition apparatus does.
One aspect of the invention involves a method of recognizing an object. The method comprises judging whether an object is detected on a lane other than a lane on which a vehicle is currently running judging whether an adjacent lane exists adjacent to the currently running lane, and recognizing that the object is a virtual image when the object is detected and the adjacent lane does not exist.
One aspect of the invention involves a method of recognizing an object by the use of a radar apparatus on a vehicle. The method comprises transmitting waves to an object ahead, receiving the waves reflected by the object, based on a signal from the receiver, judging whether the object is detected on a lane other than a lane on which the vehicle is currently running, judging whether an adjacent lane exists adjacent to the currently running lane, and recognizing that the object is a virtual image when the judgment unit has judged that the object is detected and the adjacent lane judgment unit has judged that an adjacent lane does not exist.
One aspect of the invention involves a method of recognizing an object by the use of a radar apparatus on a vehicle that can detect a range of velocities and have a detection period. The method comprises establishing a detection area in a traveling direction of the vehicle that is currently running on a lane, for detecting an object by radar waves of the radar apparatus, establishing a first area within the detection area on an adjacent lane adjacent to the currently running lane, the first area designated by a distance decided by a maximum velocity of the detection range and the detection period, establishing a second area within the detection area, not overlapping the first area, and detecting the object for the first time in the second area, not in the first area, whereby the object is judged to be a ghost.
Advantageously, the distance is decided by multiplying the maximum velocity of the detection range by the detection period.
One aspect of the invention involves a method of recognizing an object by the use of a radar apparatus on a vehicle that can detect a range of velocities and have a detection period. The method comprises establishing a detection area in a traveling direction of the vehicle that is currently running on a lane, for detecting an object by radar waves of the radar apparatus, establishing a first area within the detection area on an adjacent lane adjacent to the currently running lane, the first area designated by a distance decided by a maximum velocity of the detection range and the detection period, establishing a second area within the detection area, not overlapping the first area, detecting the object for the first time in the second area, not in the first area, and detecting a target vehicle that runs at the same distance and relative velocity of those of the object, whereby the object is judged to be a ghost.
Advantageously, the distance is decided by multiplying the maximum velocity of the detection range by the detection period.